The third field test was made on the occasion of dye diffusion experiments done in the 

 middle of March off Panama City, Florida. On March 12th we mounted the instrument on a 

 Navy tower 12 miles off shore. The height of the platform above the sea surface is about 

 100 feet. (Gaul, 19G3) In this field test, two bits of evidence were found to demonstrate the 

 usefulness of the IRT to detect a fine temperature structure. Figure 5 indicates the record 

 of the IRT in the case of passage of a tide line. The BT data are also showTi in this figure. 

 The mercury thermometer readings show the increase of 0.6°F after the passage. The sharp 

 rise in the record corresponds to this increase. Figure 6 shows the change of IRT readings 

 in the wake of a boat with a draft of about 7 feet. On this day, air temperature is colder than 

 the sea surface temperature and thus the temperature of the surface film seems to be much 

 lower than the bucket temperature. This decrease of surface film temperature could not be 

 detected by BT. However, the increase of IRT readings by about 0.6' F suggests the existence 

 of such a film. 



In concurrent use of the IRT with dye experiments, it was found that both the fluor- 

 escein dye and rhodamine "B" dye seem to raise the IRT readings. The actual traces of the 

 IRT on board a ship and on the stage are shown in Figure 7. The former indicates the rise 

 of IRT readings at the edge of the rhodamine "B" dye patch. 



It is interesting that the subsequent main part of the dye patch did not show any change 

 in the IRT record although the patch was clearly visible on board the ship and from an air- 

 plane. This is consistent with other observations that dye is close to the surface of the lead- 

 ing edge of dye patches but is found deeper in the trailing part (Ichiye. 1964). The latter 

 shows also a jump of about 1.0 to 2.0 'F when the dye patch was passing. Later laboratory 

 experiment indicates that the rhodamine "B" dye increased the IRT readings by 1.5' F im- 

 mediately when the powdered dye was added and by 2.5° F after the surface film was formed 

 in water of 66.0° F. 



Figure 5. Effect of a tide line passing IRT fixed on Panama City Tower. 

 Bathythermogram shown at left foi- some time and place 



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